1. Field of the Invention
This invention relates to a device for detecting a moving object, and more particularly to a device for detecting the presence of a sheet-like object such as a sheet of original or copy paper transported along a transport passage in a rotary camera, copier or printer.
2. Description of the Prior Art
In a detector device of the described type heretofore known, a light source and light receiving element are disposed in opposed relationship with a transport passage intervening therebetween and a moving object intercepts the optical path between the light source and the light receiving element to thereby enable the presence of such object to be detected.
However, since the sheet-like object is variable in width, it may happen that the object is transported outside the optical path to thereby prevent itself from being detected. In some cases, the sheet-like object may be transported with its leading edge disposed obliquely with respect to the direction of transport, thereby causing a time delay in the detection, and this is undesirable in that part of the object fails to be photographed or recorded if the object is to be photographed or copied simultaneously with the detection.
In order to avoid such disadvantages, it has heretofore been practised to provide a plurality of light sources and a corresponding number of light receiving elements in the transport passage for the object to thereby form a number of detecting optical paths, but this has involved the use of numerous elements or means which in turn has resulted in an enlarged size and increased cost of the entire device.